A fuel cell is a device which converts chemical energy to electrical energy through an electrochemical reaction (see, for example, Patent Literature 1). A solid oxide fuel cell, which is a class of such fuel cell, has layers of a fuel electrode, a solid electrolyte, and an air electrode stacked together to serve as a power generation unit of the fuel cell, and is configured to supply the fuel electrode with a fuel gas such as hydrogen or hydrocarbon from the outside and to supply the air electrode with an oxidant gas such as air, thereby generating electricity.
In general, a cell being a power generation unit of a fuel cell is sandwiched by current collectors which collect electrons from a fuel electrode and an air electrode. Moreover, each of the current collectors functions as a separator which defines a fuel flow path and an air flow path. In addition, there is a cell that is supported on a metal support for ensuring strength to have a stack structure of the metal support, the fuel electrode, the solid electrolyte, and the air electrode.